Recording and reproducing sound



Och 1933- H. A. SIMPSON El AL RECORDING AND REPRODUCING SOUND Filed June 25, 1931 2 Sheets-Sheet 1 93 H. A. SIMPSON Er AL RECORDING AND REPRODUCING SOUND Filed June 23, 1931 2 Sheets-sheaf. 2

swmmm WWW E A s a Ma Hf Patented Oct. 3, 1933 1 1,328,953 7 RECORDING AND REPRQDUCIN G SOUND Hobart A. Simpson, 'Ocean. Grove, and Thomas D. Burlransg Highlands, N. J., assignors, by direct and mesne assignments, to Jones Research Sound Products, Inc., a corporation of New York Application June 23, 1931. Serial No. 546,196 claims. '((3l. 179--- 100.3).

This invention relates particularly to sound recording and reproduction inconnection with motion picture film. i r

Becauseof practical limitations in the width I of strip available for the sound record at the side C of angle recording hereinafter fully described of the picture frames, the quality of the recording has tolsome extent been handicapped in.

methods heretofore employed. l

, Special objectsof this invention are to'make an accurate sound record, that is one of unlimited frequency response, without increasing the width'of the sound track and further to actually reduce the width of the film track and hence gain added picture space on the film.

These objects are attained by the novel method and broadly claimed. i v

The drawings accompanying and forming part of the a specification; illustrate various embodiments and practical features of the invention but, as will be clear from the breadthof the claims, the structure may be'modified in various ways without departure from the true spirit and broad scope of the invention. Fig 1 is a broken part sectional view illustrating sound recording apparatus embodying features of the invention; Fig. 2 is a broken detail a view, lookingin the direction ofarrow 2 in l andshowing in particular the inclined record ing slit in relation'to the film. V

' Figs. 3 and 4 are comparative views illustrating a narrow widthfllm track produced by thisinventionand of a greater frequency range, than the much wider track produced according to socalled variable density modern methods of recording; Figs. ,5 and 6 are'similar comparative views illustratingthe narrow sound track of the present invention in relation to a variable area track of modern recording Fig. 'Tis a fragmentary sectional view illustratinga modified form .of glow tube, which may be useddirectly with the inclined slit without the interposition of a condensing lens; Fig. 8 isa broken sectional view illustrating an opticaltyp'e of inclined slit; Figs. 9 and 10 are fragmentary views illustrating the thirddimensionalefiects of this new'recording on standard size and on the small lti mmg'size film; Fig. 11 is a diagrammatic illustration of the sound recordings on a greatly magnified scale; Fig. 12 is a diagrammatic illustration of the special hook-up employed for recording;

Fig. 13 is a somewhatdiagrammatic illustration of the reproducing apparatus;

prising a sound modulated glow tube or exciter lamp 14, supported in line with the optical tube 15, carrying the lens system focused on the constantly travellingfilm 16. The optical system illustrated, consists of the lenses 1'! for condensingrthe light from the glow tube through the slit 18, in the plate 19, onto the projecting lenses 20.

The optical tube is shown slidinglymounted in the holder 21 for focusing purposes and as adjustedin such relation by the rack and pinion mechanism 22. l

The light slit 18 differs from the conventional, in that it is inclined to the longitudinal axis of the film,'instead of at right angles thereto. This will be clear particularly from Fig. 2.

For thepurpose of fixing and predetermining the incline'or slant of the light slit, the barrel or tube of the optical system is rotatably jour, nalled in the focusing sleeve 23 and is equipped "with a worm gear. segment 24, engaged by a hand operated worm- 25 mounted on sleeve 23., The worm gear segment is shown as cut in a ring 26, fixed to the lens barrel andforming an abutment at one end of the focusing sleeve and a similar ring 2'7 is shown fixed to the barrel at the oppoterfering with or being affectedby the focusing adjustment.

. The-glow tube holding-sleeve 28 is shown as adjustable in the socket 29, toward and away from the end of the-lens tube by'the manually operable rack and pinion 30. For locating the glow tube in the holder, the tube is shown gripped by the spring Dads 31,.0f a surrounding sleeve 32, shiftablyr engaged at 33 by'a screw 34, turning in the holder 28'and secured by a locknut 35. By such construction,:the tube is resiliently'supported and may be readily'centered with respect to the in- ,clined light slit and this without interfering with the longitudinal adjustment of the tube holder with respect to the lens system. Apreferred form of recording circuit is illustrated'in Fig. 12, where a microphone or pickup --is indicated at 26, connected with'an audio amplifier 37, feeding intoa transformer 38, connected'by leads 39, 40, directly with the electrodes of an exciter'tube; A level indicator is shown connected acrossthese leads at 41, for following the tube actionand the energizing source for the tube is indicated at'42, connected with a variable 'resistance'43 tothe'two leads of the tube.

In order that the results attained with this invention may be better appreciated, there is illustrated in Fig. 3, a section of film witha sound track 44 thereon as produced by the apparatus described. This view shows how with the slit set at an angle to the longitudinal travel of the film there will be photographically producedon' the film lines 45 of variable intensity in parallel relation, but inclined to the longitudinal extent of the film, forming a sound track which is narrower than the customary variable density soundtrack 44a indicated in Fig. 4, but with the individual lines of recording actually' as long or, if desired, the longer.- This not only provides unlimited frequency response, but allows greater transverse width 46 for the picture area on the film.

Actually, it is found thatthe inclined line recording gives a third dimensional effect, such as illustrated in Fig. 9, where it is shown 'that the liens may be of both variable density and of variable length. I

Thesaving in transverse width of the sound track is sojmarked, that it has been found possible .to run a soundtrack on the narrower width film, commonly known as a 16 mm. film, as illus-. trated in Fig. 10,-a result desired but heretofore impossible of attainment in the narrower forms of picture film. 1

The same advantages are attained, in this invention, for constant density variable area methreproducing apparatus is modified to the extent that the light'slit 18a isinclined to accord with the inclination of the record lines as illustrated in Fig. '13, which is'a somewhat general showing of a sound head for a projector. This sound head may have a fixed angle'slit or the angle may be adjustable by means suchas illustrated in connection with the sound'ca'mera'shown in Fig. 1. If found desirable, to change the inclination for dilferent types of recording, the angle may be marked on the film or the information be otherwise applied, so that the operator of the-projector maycorrespondingly set the'inclination of the slit in the sound head, for instance, through the mediumof suitable angle markings on theflens tube,

orthe'like.

The structure employed maybe modified in various ways. For example, as indicated in Fig. 7., the condensing lens at the recorder may be omitted and theilight be furnished direct to the slit by making the glow tube with a smaller end extensionl4a and providing a light collecting reflector 48 for focusing the light from thesmaller extension directly to the inclined slit. This permits of a more compact'arrangement with the larger portion of the glow tubeto one side of and substantially at right angles to the lens tube.

Also, the light slit may be of the optical, as distinguished from the mechanical'type, such as indicated in Fig. 8, where the opposed inclinedreflectors 49, 50, interposedbetween the condensing and projecting lenses transform the light from the glow tube into a line on the film, the inclina- .tion .of. which is governed by the rotationalsetting of the lens tube accomplished by the worm or screw adjustments 24, 25. V j

By the angle recording method of this inven-.

from full width film onto 16 mm. or narrow =film tion,=the new result illustrated in Fig. 11 is accomplished, that is, a record line is produced involving a constant length 51, determined by the length of the light slit, plus the variable more or less pointed tips 52 at the ends of the constant length section; 7 These endsappear .as fringes or peaks 'varying'i'n shape from the sharply pointed areas-to the more rounded areas shown and this "reproduction, which has not been accomplished heretofore, believed to be due. to the greater frequency range, without cut-off. Thus a variable area repording effect is obtained without any mechanical shutter devices or other such elements as would introduce a lag or create a lack of synchronism.

The angle or inclination of the record lines may vary, but'preferably it is between ,to 89 to the horizontal or transverse dimension of the film. Within this range, the lines are actually longer than :the horizontal recording on standard motion picture film and the overall width of the track is less than one-third the width of the usual sound track. The gain in available picture area is thus .considerableand the quality of sound reproduction is much improved. .Also, it will be noted, .the so-called fnoise area is cut down by by" photographic reproduction :methods to produce for example, the sound picture film shown inl'ig. '10. r I l p I It has been proposed heretofore, to produce 16 mm. sound film by printing according to 'photographic reduction methods from the 35 mm. commercial film :onto 16 mm. .fllm, but this has not been practical, because the reduction in scale of the sound track has requiredso much amplification to be used as'to distort and substantially destroy the sound'values. The present invention makes it possible to reprint from '85 mm. to 16 mm.-so1md-film without impairing the sound record. For this special purpose, the angle recording on the 35 mm. film can be made equal in width to the present sound track now used with film, giving 'a length of line, which after reduction in printing onto the 16 mm. film will still .be Onger than the lines on the present 35 mm. film. .Thus a record is produced .on '16 mm. film equal to present recordings on 35 mm. film."

For general commercial purposes, the inclination of the light slits in the soundcameras and in the sound heads may be fixed at the same angle, so that film produced in any sound camera will'be "ready to run in any projector. If desired however, the projector may be so constructed as to permit of a range of angular adjustment and particularly for example, the range of adjustment necessary to shift from a'standard horizontal line recording over to the new angle recording or vice versa. Thus, the entire optical system of the projector, including the mounting of the excitorlamp may be soconstructed .thatit will carry the slit from the horizontal to the desired angular position or from the inclined slit position back to the horizontal position, stop shoulders for instance, being provided to'limit the'rotational throw of the optical system in either direction and a holding pin or pawl or the like, may be provided to releasably secure the optical tube in either one position or the other. It will be understood that the shifting of the light beam from the horizontal to the inclined or vice versa, may be accomplished purely by optical means, such as shown in Fig. 8, in which adjust-' ment of the mirrors will accomplish what is efiected by angular adjustment of the slit.

The variable area constant density recording illustrated in Fig.5 may be produced by oscillographic methods with the reflecting prism arranged to transcribe the record lines inclined to the longitudinal axis or direction of travel of the film, instead of horizontally or transversely of the I film as heretofore. I v

' sound camera, the inclination of the light record lines being between 75 and 89 to the transverse dimension of the film.

2. In motion picture sound recording and reproducing, the combination of sound recording and sound reproducing mechanisms having light slits inclined at the same angle to the direction of film travel and within the range 75 and 89 to the transverse dimension of the film.

3. A sound head for a motion picture projector,

comprising an optical system including means for creating the eifect of a light slit inclined to the direction of film travel through the head between 75 and 89 to the transverse dimension of the film.

composed of variable sound record lines in parallelism and inclined to the longitudinal extent of the film.

5. In motion picture sound recording and reproducing, the combination of sound recording and sound reproducing mechanisms having optical systems for creating the effect of light slits inclined at the same angle to the direction of film travel and within a range on the order of 75 to 89 to'the transverse dimension of the film.

HOBART A. SIIVIPSON. THOS. D. BURHANS.

4. As a new article ofmanufacture, afilm having a constant width sound track thereon and 

